Methods and apparatus for directional drilling

ABSTRACT

In each of the several embodiments of the apparatus of the invention disclosed herein, a new and improved tool carrying a drill bit is dependently coupled from a drill string and lowered into a borehole which is to be excavated in a desired direction. First and second sets of wall-engaging members are operatively arranged around the tool in such a manner that as the weight of the rotating tool is successively supported by each of the first members, commensurate outwardly directed forces will be successively imposed on each of the second members for urging the drill bit in a desired lateral direction. Various controls adapted for operation from the surface of the earth are disclosed for selectively interconnecting the first and second wallengaging members so as to either maintain the course of the drill bit along a vertical axis or else to direct the drill bit in a selected azimuthal direction and inclination. In practicing the methods of the present invention, a tool arranged in accordance with the invention and having a drill bit connected thereto is coupled in a drill string and positioned in a borehole. Depending upon the particular tool, the controls on the directional drilling tool are then regulated from the surface to direct the drill bit along a selected source for continuing the excavation of the borehole.

United States Patent [72] lnicntm Roger Q. Fields Houston, Tex. [21 IAppl. No 865,884 [22l Filed Oct. 13. 1969 [45] Patented July 20, 1971[73] Assignee Schlumberger Technology Corporation New York, N.Y.

[54] METHODS AND APPARATUS FOR DIRECTIONAL DRILLING 37 Claims, 28Drawing Figs.

[52] U.S.Cl 175/61, 175/76 [51] Int. Cl E2lb 7/08, E2lb 7/04 [50]FieldofSearch 175/73,61 74, 76

[56] References Cited 1 UNITED STATES PATENTS 3,098,534 7/1963 Carr etal 175/73 3,141,512 7/1964 Gaskelletal. 175/73 3,196,959 7/1965Kammerer... 175/73 3,243,001 3/1966 Vincent 175/73 3,298,449 111967'Bachman et al.. 175/76 Primary Examiner-James A LeppinkAttorneys-Ernest R, Archambeau, Jr., William J. Beard,

Stewart F. Moore, David L. Moseley, Edward M. Roney and William R.Sherman ABSTRACT: In each of the several embodiments of the apparatus ofthe invention disclosed herein, a new and improved tool carrying a drillbit is dependently coupled from a drill string and lowered into aborehole which is to be excavated in a desired direction. First andsecond sets of wall-engaging members are operatively arranged around thetool in such a manner that as the weight of the rotating tool issuccessively supported by each of the first members, commensurateoutwardly directed forces will be successively imposed on each of thesecond members for urging the drill bit in a desired lateral direction.Various controls adapted for operation from the surface of the earth aredisclosed for selectively interconnecting the first and secondwall-engaging members so as to either maintain the course of the drillbit along a vertical axis or else to direct the drill bit in a selectedazimuthal direction and inclination. In practicing the methods of thepresent invention, a tool arranged in accordance with the invention andhaving a drill bit connected thereto is coupled in a drill string andposi' tioned in a borehole. Depending upon the particular tool, thecontrols on the directional drilling tool are then regulated from thesurface to direct the drill bit along a selected source for continuingthe excavation of the borehole.

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IN VE N TOR ATTORNEY METHODS AND APPARATUS FOR DIRECTIONAL DRILLING Indrilling of an oil well, it is well known that variations in the weightapplied to the drill bit, the rotative speed, and the rotative directionwill often inadvertently deviate the borehole from its intended axis. Onthe otherhand, in many drilling operations it may be necessary to drilla deviated borehole having a desired inclination as well as a selectedazimuthal orientation. In such situations, the drill bit is deliberatelydiverted so as to pass a borehole obstruction or to reach a specifiedtarget area that is at a considerable depth and horizontal displacementfrom the drilling rig at the surface.

It has been the usual practice heretofore to employ socalled whipstock"tools or the like for either deviating a borehole toward a desiredlocation or returning it to an intended axis. Some typical whipstocktools include a wedgelike body that is slidably mounted on the drillstring and has an inclined longitudinal face. Once this slidably mountedbody is positioned in a desired orientation along one side of theborehole, a small-diameter drill bit on the drill string is advanceddownwardly along the inclined face of the body and diverted accordinglyin a desired direction and inclination to excavate a reduced-diameterpilot hole for some distance into the formation. The whipstock andsmaller drill bit are removed from the borehole and a full-sized bit isthen run in on the drill string t4 enlarge or ream the smaller pilothole. This operation is repeated as many times asis necessary toaccomplish the desired job. i

To avoid such time-consuming whipstocking operations, other tools havealso been employed which generally include an assembly having one ormore manually positioned deflecting members arranged thereon. Once thesedeflecting members are secured in a desired configuration at thesurface, the assemblyis run into the borehole immediately above thedrillbit. Then, once the tool assembly has been properly oriented from thesurface, drilling is commenced and the fixed deflecting members willhopefully divert the drill bit along a desired axis. It will beappreciated, however, that with even such improved tools, the directionand inclination of the borehole must be frequently. checked; and, if itis discovered that the borehole is not being deviated properly theassembly must be returned to the surface for making correctiveadjustments. It is readily apparent, of course, that evenan infrequentreturn of the drill string and tool assembly to the surface for suchadjustments constitutes a time-consuming and, therefore, an expensiveoperation.

Accordingly, it isan-object of the. present invention to provide new andimproved methods and apparatusfor-selectively guiding adrill bit as itprogressively excavates aborehole, with the guidance being accomplishedduring the course of the drilling operation without removing the drillstring from. the borehole for corrective adjustments.

This and other objects of the present invention-are attained byproviding a directional well-drilling tool having pressureactuatedguiding means operatively mounted abovea drill bit for deflecting thedrill bit along selectedaxes of excavation in response to the lateralmovements of deviation-sensing pressure-developing means. arrangedon thetool and. selectively coupled-to the guidingmeans by oneof severalembodiments.

of selectively operable control meanscarriedon' the tool. In some of thedisclosed embodiments of the present invention, pressure-responsivecontrol means arearranged on the tool in such a manner that by simplyincreasingthe pressure of the drilling fluid flowing through the drillstring to at least a predetermined magnitude, a'selected couplingarrangement will be established between the deviation-sensingmeans andthe guiding means. In alternate embodiments, the control means areselectively controlled by. actuating members adapted to. be dispatchedfrom the surfacethrough the drill string to the directional tool. Byarranging particular surfaces of these actuating members tocooperatively engage matching surfaces on the control means, thedeviation-sensing means and guiding means are selectively coupled in anyone of several predetermined arrangements. Another embodiment employscontrol means adapted for operation in response to predeterminedmanipulations of the drill string to couplethe deviation-sensing meansand guiding means.

The novel features of the present invention are set forth withparticularity in the appended claims.

The invention, together with further objects and advantages thereof, maybe best understood by wayof the following description of exemplaryapparatus and methods employing the principles of the invention asillustrated in the accompanying drawings, in which:

FIG. I depicts one embodiment ofa directional drilling tool arranged inaccordance with the principles of the present invention as it may appearwhile a deviated borehole is being drilled by practicing the methods ofthe invention;

FIGS. 25 are cross-sectional plan views respectively taken I along thedesignated section lines in FIG. I and showing various details of thedirectional drilling tool illustrated there;

FIG. 6 is a somewhat schematic, developed view of a portion of theapparatus depicted in FIG. 1;

FIGS. 7 and 8 are two views showing one embodiment of apressure-responsive actuator which may be used for controlling thedirectional drilling tool shown in FIG. 1;

FIGS. 9 and I0 are two views of an alternative pressureresponsiveactuating mechanism that may also be used with the tool depicted in FIG.I;

FIG. II illustrates an alternative embodiment of a directional drillingtool generally similar to that shown in FIG. I but including additionalnew and improved features;

FIGS. 12-14 are cross-sectional views of the directional drilling tooldepicted in FIG. II respectively taken along thedesignated section linestherein;

FIG. 15 is a developed view schematically illustrating one embodiment ofa mechanically actuated control for the directional drilling tool shownin FIG. II;

FIG. 16 depicts an actuator adapted for use with the control shown inFIG. I5;

FIG. I7 is a developed view schematically representing an alternativeembodiment of a mechanically actuated control for the directionaldrilling tool illustrated in FIG. II;

FIG. 18 is a cross-sectional view of a portion of the control shown inFIG. I7; t

FIG. I9 illustrates one embodiment of an actuator adapted for use withthe control illustrated in FIGS. 17' and 18;

FIG. 20 is an elevational cross-sectional view of still anotherembodiment of a directional drilling tool also incorporating theprinciples of the present invention;

FIGS. 21 and 22 are cross-sectional plan views'respective'l taken alongthe lines 2l2I and 2222-in FIG. 20;

FIG. 23 is a schematic representation of the control system of thedirectional drilling tool illustrated in FIG. 20;

FIG. 24 illustrates an alternative embodiment of a control device forthe directional drilling tool shown in FIG. 20;

FIG. 25 depicts a further embodiment of a directional drilling tool alsoarranged in accordance with the principlesof the present invention;

FIGS. 26 and 27 are cross-sectional views taken alongthe designatedsection lines in FIG. 25;;and I FIG. 28 is a developed view of a portionof the tool shown in FIG. 27.

DESCRIPTION OF THE TOOL DEPICTED IN FIGS. I'- I0 tool-30 for operationin the usual manner uponrotation of the drill string 3] by a typicaldrilling rig (not shown) at the surface. As illustrated, the directionaldrilling tool 0 has an elongated, thick-walled tubular housing 34 withan axial bore 35 therethrough to permit the usual circulation ofdrilling fluids or so-called mud from the surface through the drillstring 31 and appropriate discharge openings (not shown) in the drillbit 33 and back to the surface by way of the borehole 32. In thispreferred embodiment of the tool 30, wall-engaging deviation-sensingmeans 36 and direction-guiding means 37 are respectively mounted on theupper and lower ends of the tool housing 34 and operativelyintercpnnected by selectively operable control means 38 adaptedto beremotely actuated from the surface. To protect the wall-engaging means36 and 37 as the directional drilling tool 30.is moved into and out ofthe borehole 31, enlarged-diameter shoulders, as at 39, are respectivelyarranged on the housing 34 immediately above and below the upper andlower wall-engaging means.

As best seen in FIG. 2, the upper wall-engaging means 36 preferablyinclude three laterally movable pistons 40 respectively disposed inoutwardly facing radial bores 4] arranged at equal intervals around theexterior wall of the tubular housing 34 and biased outwardly by springs42. A circumferential band 43 encircles the tool housing 34 between theseveral enlarged shoulders 39 and carries on its outer face threeoutwardly projecting wall-contacting members 44 respectively disposedadjacent to the outer ends of each of the pistons 40.

To prevent-significant rotation between the band 43 and tool housing 34,the circumferential band is loosely keyed, as at 45, to the shoulders39. As illustrated in FIG. 3, the lower wall-engaging means 37 alsoinclude three pistons 46 arranged in uniformly spaced radial bores 47 inthe housing 34 aswell as a circumferential band 48 supporting threecircumferentially spaced wall-contacting members 49. Although the upperand lower wall-engaging means 36 and 37 are preferably identicallyarranged, it will be noted in FIGS. 1--3 that the upper and lowerwall-engaging means are angularly offset 60 from one another on the toolhousing 34.

The upper piston cylinders 41 (FIG. 2) are filled with a suitablerelatively noncompressible fluid, such as a hydraulic oil, andrespectively fluidly coupled by flow conduits, such as separate tubinglines or fluid passages 50 and 51 in the tool housing 34, and .thecontrol means 38 to the fluid-filled piston chambers 47 (FIG. 3) of thelower wall-engaging means 37. In this manner, depending upon theparticular operating position of the control means 38, inward movementof one of the upper pistons 40 will develop an increased hydraulicpressure for producing a corresponding outward movement of a selectedone of the lower piston members 46 of the direction-guidingwall-engaging means 37. For example, assuming that the fluid conduits50a and 51a are fluidly coupled to one another by the control means 38,each time the piston 400 immediately adjacent to the upperwall-contacting member 44a is moved inwardly by the weight of the tooland drill string 31, the corresponding outward movement of the piston46a will in turn urge the lower wall-contacting member 490 outwardly.

As illustrated in FIGS. I and 6, therefore,, with the control means 38selectively interconnecting the conduits 50a and 510 each time the drillstring 31 is rotated so as to bring the upper wall-contacting member 44ainto contact with the lower surface of the borehole 32, thecorresponding outward movement of the lower wallcontacting member 490will, of course, impose a downwardly acting force on the drill bit 33that is proportionally related, if not equal, to the inwardly actingforce on the upper wall-contacting member. Similarly, with .the controlmeans 38 fluidly c4ueling the upper and lower pistons 40b and 46b, eachtime the upper wall-contacting member 44b is rotated into position alongthe lower surface of the borehole 32, a corresponding outwardly directedforce will be applied t4 the wall-contacting member 4% which is at thistime against the upper surface of the borehole. Then, since the thirdpiston 400 is also coupled by the control means 38 for actuation of thelower piston member 46c, as the drill string is rotated to bring theupper wall-contacting member 44c into contact with the lower surface ofthe borehole 32 the lower wall-contacting member 490 (which is now atthe upper surface of the borehole) will in turn be u7ged upwardlyagainst the borehole wall so as to directed force on the drill bit 33.

Thus, it will be appreciated that as the drill string 31 is rotated, theupper wall-contacting members 44 will be successively brought intocontact with the lower surface of the borehole 32 and, in turn, be movedinwardly by the weight of the tool 30. In this manner, when the upperand lower wall-enagairi impose a downwardly gaging means 36 and 37 arefluidly coupled in the manner just 4-6, in one manner of accomplishingthis, the control means i 38 include an annular valve member 52rotatively mounted in a complementary outwardly directed recess oropening 53 formed around an intermediate portion of the tool body 34.

To permit the rotatable valve member 52 to rotate with relative ease inrelation to the tool body 34, a suitable bearing 54 (FIG. 8) is mountedbetween the rotatable valve member and the body of the tool 30. Thefluid passages 50 from the three piston chambers 41 of the upperwall-engaging means 36 are carried down the tool housing 34 andrespectively terminated at equally spaced intervals around thedownwardly directed upper face of the peripheral recess 53 in the toolhousing. Similarly, as best seen in FIGS. 4'6, the fluidpassages 5Irespectively coupled to the piston chambers 47 of the lowerwall-engaging means 37 are brought up the tool body 34 and, by means ofappropriately arranged branch passages 55c, terminated at the upwardlydirected lower face of the housing recess 53 in such a manner that eachof the three passages from the lower piston chambers is terminated bythe branch passages at three equally spaced intervals around thecircumference of the lower recess face. Generally arcuate recesses 56are formed in the upper face of the rotatable valve member 52 andrespectively disposed therearound through an arc of less than I20.Single downwardly directed ports 57 are respectively formed in the lowersurface of the arcuate recesses 56 so as to provide communicationtherefrom to the lower face of the rotatable valve member 52.

Accordingly, as schematically illustrated in the developed view in FIG.6, by spacing the several branch passages 55 at uniform intervals aroundthe circumference of the lower surface of the housing recess 53, each ofthe ports 57 will be facing one of the branch passages in selectedincremental positions of the valve member 52 in relation to the toolhousing 34. Furthermore, by virtue of the arcuate recesses 56, thepassages 50 will be respectively communicated to one of the three branchpassages 55 adjacent to the ports 57 in these incremental angularpositions of the rotatable valve member 52. It will be appreciated,therefore, that by arranging the branch passages 55 in the mannerillustrated, each of the upper piston chambers 41 will be sequentiallyconnected in turn to each of the lower piston chambers 47 as thevalve-member 52 is successively positioned between its severalincremental positions. Moreover, in other incremental positions of therotatable valve member 52, the fluid passages 50 and branch passages 55will be fluidly sealed (as by the seals 58 and 59) by the body of thevalve member so as to block communication between the upper and lowerpiston chambers 41 and 47. Thus, as illustrated in FIG. 6, the valvemember 52 can be selectively moved to attain any one of four operatingconditions which, are respectively determined by the particularincremental angular position of the valve member in relation to the t4olhousing 34. I?

In the particular operating positionof the-valve member 52 schematicallyillustrated in FIG. 6, the piston chamber 410 is chamber 47b, with theother two upper piston chambers 41b and 41c being similarly coupled tothe lower piston chambers 47c and 47a respectively. Similarly, byindexing the rotatable valve member to its next incremental position, adifferent combination of interconnection between the upper and lowerpiston chambers 41 and 47 will be accomplished. in at least the fourthincremental position of the rotatable valve member 52, nointerconnection is provided between the upper direction-sensing means 36and the lower direction-guiding means- 37 such as, for example, when theport 57a is between the passages 55c and 55b.

In one manner of selectively moving the rotatable valve memberto itsvarious incremental angular positions, pressureresponsive actuatingmeans 60 are conveniently located as seen in H08. 7 and 8 adjacent tothe housing recess 53 and operatively arranged so that successivetransmissions of an increased pressure of selected magnitude will beeffective to rotatively shift the valve member 52. To accomplish this, apiston member 6! is slidably mounted for reciprocating upward anddownward movement in a piston chamber 62 formed in the tool body 34immediately above the outwardly directed annular recess 53. A dependingaxial projection 63 from the piston 61 is extended downwardly therefromthrough an opening 64 in the upper surface of the housing recess 53 andappropriately arranged for carrying a pivotable pawl 65, A plurality ofequally spaced ratchet teeth 66 are formed in a circumferential patharound the upper face of the rotatable valve member 52 directly belowthe pawl 65.

It will be appreciated, therefore, that whenever the piston 61 is moveddownwardly, the free end of the pawl 65 will be moved downwardly acrossthe inclined face, as at 67, of one of the teeth 66 until halted bycoming into engagement with an opposing upright face 68 of the nextadjacent tooth. Then, upon continued downward movement of the piston 61,the pawl 65 will be effective to shift the rotatable valve member 52 tothe right (as viewed in FIG. 7) until the piston has reached the lowerlimit of its downward travel. Upward travel of the piston 61 will, ofcourse, retract the pawl 65 and restore it to its initial positionimmediately above the next adjacent tooth 66. Thus, upon successiveupward and downward strokes of the piston 61, the rotatable valve member52 will be incrementally shifted through a predetermined arc of travel.

in one manner of actuating the piston 61, a spring member 69 is arrangedin the piston chamber 62 for normally urging the piston upwardly and afluid passage 70 is provided between the upper portion of the pistonchamber and the central bore 35 through the tool housing 34. A secondfluid passage 71 is provided for communicating the lower portion of thepiston chamber 62 with the exterior of the directional drilling tool 30.Accordingly, by imposing a higher fluid pressure above the piston 61than that presently existing therebelow, the piston will be urgeddownwardly to accomplish the above-described angular indexing movementof the rotatable'valve member 52.

In one manner of providing this increased fluid pressure, thefluid-circulating or mud pumps at the surface can be readily operatedinsuch a manner as to produce a greater fluid pressure in the centralhousing bore 35 than that existing in the borehole 32 exterior of thehousing 34. Thus, once the fluid pressure in the axial bore 35 hasincreased sufficiently to compress the spring 69, the piston 61 will beshifted downwardly until it is halted by the pawl 65 reaching its lowerlimit of travel in-relation to the rotatable valve member 52. To assurethat the piston 61 is not inadvertently actuated by minor variations inthe pressure of the circulating fluid or mud, the spring 69 isappropriately selected so as to require a significant increase in fluidpressure over the hydrostatic pressure ofthe mud column in the borehole32. Thus, so long as the circulating fluid is maintained in its usualrange of pressure conditions, the operator can be certain that thedirectional drilling tool 30 is properly adjusted for directing thedrill bit 33 in the then selected manner. Then, should it becomenecessary during the course of the drilling operation to make acorrection such as by shifting the valve member 52 to either anotheroperating position or to an inoperative position for interrupting thedirectional control of the tool 30. this can be simply accomplishedbyone or more brief increases of the circulating pressure. It will beappreciated that successive increases of the circulating pressure willreadily index the rotatable valve member 52 through each of its severalpositions before it is again returned to its initial operating position.i

. Turning now to FIGS. 9 and 10, an alternative embodiment is shown ofselectively operable pressure-responsive actuating means 60' that aregenerally similar to the pressure responsive actuating means 60 justdescribed. The actuating means 60' similarly include a piston member 61that is adapted for reciprocating vertical movement in the pistonchamber 62 immediately above the rotatable valve member 52'. Thepressure-communicating passage 70 is similarly provided forcommunicating the pressure in the axial bore 35 of the tool 30 to theupper portion of the piston chamber 62 and the other passage 71 againcommunicates the lower portion of the piston chamber with the borehole32. Thus, an increase in pressure in the axial bore 35 sufficient toovercome the upwardly directed biasing force ofthe compression spring 69will also shift the piston 61' downwardly toward the valve member 52'.

To selectively index the valve member 52 between its vari ous angularpositions, the depending shaft 63' of the piston 61' is provided with anoutwardly directed cam which, preferably, is a laterally orientedroller65'. The roller 65' is operatively received within a labryinthlikesystem of alternately inclined cam grooves 66 formed around the internalsurface of the valve member 52 to provide a continuous alternating trackupwardly and downwardly around the internal wall of the rotatable valvemember. In this manner, each downward movement of the piston member,6lthe roller 65' will be effective for camming the valve member 52 to theright as viewed in FIG. 9 until the roller reaches an upwardly facingpocket, as at 72, formed at the lower junction of two adjacent grooves66. Then, upon upward movement of the piston member 6] the roller 65'will cam the valve member 52 still further to the right until the pistonmember again reaches its normal elevated position with the roller comingto rest in a downwardly facing pocket as at 73; Thus, by arrangingadjacent pairs of the grooves 66' to span a selected angular interval,each successive upward and downward movement of the piston 61' will beeffective to shift the valve member 52 to its next angular position inrelation to the tool housing 34.

It will be appreciated that with the directional drilling tool 30 asshown in FIGS. l6,having either the actuating means 60 or the actuatingmeans 60', the valve member 52 (or 52') may be selectively indexed tosuccessive angular positions as desired to either isolate thewall-engaging means 36 and 37 or else interconnect the upperwall-contacting'members 44 with the lower wall-contacting members 49 inany of their three operating arrangements. Moreover, by virtue of theability to selectively operate the valve member 52 (or 52') from thesurface, the particular order of interconnection between the upper andlower wall-engaging means 36 and 37 may be varied as required simply bymomentarily increasing the pressure of the circulating fluid or mudpassing downwardly through the drill string 31 to a magnitude sufficientto at least overcome the bias of the spring 69 and shift the pistonactuator 61 (or 61) downwardly so as to leave the valve member 52 (or52') at a selected angular position whenever pressure is again restoredto its usual operating value. Thus, by making periodic surveys withtypical borehole-orienting devices such a drill bit 106 is dependentlypl -ferentially spaced at 90 interv DESCRIPTION OF THE TOOL DEPIC'IED INFIGS. I 1 -19 It will, of course, be appreciated that some situationsmay require more positive regulation for directing the course of aparticular directional drilling operation. Accordingly, analternativetool I is shown in FIG. II which is capable of being selectivelycontrolled from the surface for movement in any one of four lateraldirections. As illustrated, the directional drilling tool I00 iscomprised ofa'thick-walled tubular housing I01 havingdeviation-sensingdirection-guiding wallengaging means 102' and- I03.:respe tively arranged'=" at its upper and lower ends and selectivelyactuated control means 104 intermediately located therebetigeeni Thelower end of a drill string 105 is coupled to the upper end of the toolI00and ed to its lower end. Although the upper and Iowerwall aging meansI02Jand 103 could be arranged as previousyd c'itibed with eren ce toFIGS. 2 and a, inthe preferred four longitudinally oriented roI upperand lower ends of the togl h using I0! as in FIG. 11;and, as seen inFIG...I2,"e ach of these rollers are respectively supported by abifurcated'bracket I09 that is operatively mounted on the outer ends ofa pair of laterally movable piston members 110 (and III) respectivelymounted in vertically aligned outwardly opening radial bores 112 (andH3) in the upper and lower ends of the tool housing.

A fluid passage I14 couples each set of the upper piston chambers 112 tothe selectively operable control means I04. As best seen in FIGS. 13 andI4, each of the four passages I14 is tenninated by the upper surface ofan inwardly directed annular recess 115 formed around the tool housingI0] and opening into the axial bore 116 therethrough. The control means104 include an annular valve member II7 that is rota tively mountedwithin the complementary housing recess I15 and adapted for rotativemovement i relation thereto between two angularly, spaced positions oneach side of a selected neutral position as illustrated. Four similar oridentical arcuate recesses 118 are formed at equal intervals around thecircumference of the upper face of the annular valve member II7 so as tobe in alignment with the four passages I I4 in all of the selectivepositions of the annular valve member.

As depicted in FIGS. I4 and 15, each of the piston chambers I I3 of thelower wall-engaging means I03 are fluidly coupled to the control means104 by suitable individual conduits 119 which may be provided by meansof either passages drilled through the tool housing [M of by fluid linesdisposed along the axial housing bore I16. These passages I19 are thenrespectively branched out as shown in FIG. 15 so that each passage hasfour branches I20 each terminating at a selected position on theupwardly facing face of the annular housing recess II5. In this manner,in any of the four operating positions of the valve member I I7, asingle port 121 in each of the arcuate recesses 118 is selectivelyregisteredwith one of the four branch passages I20. In the fifthorneutral position of the valve member II7 illustrated in FIG. 15, thepoIts III are displaced from the several branch passages I20 and fluidlysealed, as by seals I22, against the lower face of the recess 1 I5.

It will be seen that with the annular valve member II7 in the neutralposition depicted in FIG. I5, there is no fluid communication betweenthe deviation-sensing means I02 and the direction-guiding means I03 soas to preclude operation of the lower wall-engaging means when, forexample,-the tool I00 is being lowered into the borehole I23. It will beappreciated,

therefore, that to selectively intercouple individual ones of the upperwall-contacting members I07 and the lower wall-contacting members I08,the valve member II7 must be shifted to one of its four operatingpositions. Accordingly, to selectively shift the valve member II7, aninwardly projecting cam member 124 is arranged on the inner wall of thevalve member in such a manner that any one of four actuating members I25such as the one shown in FIG. I6 can operatively shift the valve memberfrom its neutral position to a selected one of its four operatingpositions.

As illustrated, the valve actuator 125 is comprised of an elongatedtubular body 126 having an axial passage I27 therein terminated at itsupper end by one or more lateral ports 128 to permit free flow of thecirculating fluid as the actuating tool is moving through the drillstring I05; An outwardly projecting lug I29 is arranged on the upper endof the actuator body I26 for reception by an .upwardly facing shoulder130 formed around the inner wall of the tool housing I01 and defining adownwardly converging guide surface terminating in an elongated narrowedvertical channel I3] having an upwardly directed lower shoulder.Accordingly, when the actuator I25 is moved downwardly through thedrillstring I05 and enters the tool housing 101, the lug'tg? will engage theconverging guide 130 irrespective .of whatever angular position theactuator body I26 may t henv be infrelation to the tool housing. Then,further downward travel of the actuating tool 125 will cause it to beturned to a selected angular position in relation to the tool housingIt" and the valve member I17 once the lug I29 reaches the terminalshoulder of the channel 131. To selectively shift the valve member II7to a desired operative'position, a downwardly facing shoulder I32 isformed around the actuator body 126 and uniformly converged upwardly tothe opposite sides of the lower end of an upwardly extending groove 133that is spiralled upwardly part way around the tool body and terminatedin a downwardly opening vertical guide groove 134 having a predeterminedangular orientation in relation to the lower entrance of the curvedgroove.

Accordingly, as the valve actuator I25 enters the upper end of thehousing bore II6, the outstanding guiding lug I29 thereon will beprogressively guided by the upwardly diverging shoulder I30 within thetool housing IOI so as to bring the valve actuator in a fixed angularorientation in relation thereto once the lug is in the narrow channel13]. As the valve actuator I25 moves into its fixed angular position,the inwardly projecting cam member 124 on the valve member II7 willengage the downwardly diverging shoulders 132 on the actuator and beguided thereby into the spiralled groove I33 as the actuator movesdownwardly toward its final resting position. Then, once the valveactuator 125 has reached its final position within the tool housing 101as may be determined by the engagement of the lug 129 with the shoulderat the bottom of the channel I31, the cam member 124 will have beenprogressive ly guided by the curved walls of the spiralled groove 133into the vertical groove 134 to rotate the valve member II7 into acorresponding operative position in relation to its initial neutralposition.

It will, of course, be appreciated that the angular displacement betweenthe lower end of the spiralled groove portion I33 and the verticalgroove portion I34 will determine the degree of angular orientation ofthe valve member II7 in relation to the tool housing I01. Thus, byproviding four individual valve actuators such as that shown at I25 inFIG. 16 withtwo of these having their respective vertical grooves 134 attwo different angular positions to the right of the entrance groove I33and the other two actuators having their vertical grooves in twodifferent angular positions to the left of the enmovement of theactuator in relation to the tool housing 101 will restore the inwardlyprojecting cam member 124 to its initial neutral position as shown inFIG. so as to again close fluid communication between the upper andlower wall-engaging means 102 and 103. Then, ifit is desired to shiftthe annular valve member 117 to another of its selected positions, theappropriate valve actuator 125 can be dropped or lowered through thedrill string 105 so as .to reposition the valve member in a desiredoperating position.

Turning now to FIG. 17, an alternative embodiment is shown ofselectively operable control means 104 which may be employed with thetool 100 for controlling fluid communication between the upper and lowerwall-engaging means 102 and 103. In this developed view of the interiorwall of the tool housing 101, the passages 114 from each of the upperpiston chambers 112 are respectively extended downwardly through thetool housing at cireumferentially spaced positions therearound. Foursets of valve members 136 areprovided with each of these four setshaving four valve members disposed in vertical alignment with oneanother and having any one of the four valves 136 in a given verticalstack will selectively connect one of the four upper piston chambers] 12v with a corresponding one of the four, lower piston chambers 113. Thus,by also arranging the four valves 136 in any 7 horizontal tier withtheir outlets respectively connected to a different one of the passages119 and 120, opening of all four valves in a given horizontal tier willconnect each of the four upper pistons 110 respectively to a separateone of the four lower pistons 111. It will be appreciated, therefore,that by selecting a horizontal tier of four valves 136'which are to beopened and by leaving the remaining I2 valves closed, e8ch of the upperwall-contacting members 107 can be respectively connected to any one ofthe four lower wall-contacting members 108. The order of the l6 valves136 is, of course, arranged so as to provide for any one of the fourpossible connections between the upper and lower wall-engaging means 102and 103.

Accordingly, as shown in FIG. 17, a specific pattern is established sothat when all four valves 136 in any horizontal tier are opened, each ofthe upper wall-contacting members 107 will be respectively connected toa selected one of the four lower wall-contacting members 108. Thus, ifthe valves 136 in the uppermost horizontal tier are all opened, forexample, the upper wall-contacting member 1070 will be connected by wayof the passage 114a and passage 120a to the lower tool housing 101 areterminated within the radial bore 141 so that the rear sealing member142 on the valve body 137 is between the entrances of these passages.Thus, so long as the valve body 137 is shifted forwardly, fluidcommunication is blocked between the two passages 114d and 120d.Conversely, it will be appreciated that movement of the valve body 137further into the radial bore 141 will shift the rearward valve seal 142to the rear of the passage 114d so as to open communication between thatpassage and the'outlet passage 120d.

. Accordingly, it will be appreciated from viewing FIG. 11 1 that as thedrill string 105 is rotated, one of the upper wall-engaging members 107will come into contact with the lower surface of the borehole 123 duringeach quarter of a given revolution. When this occurs, the, combinedweight of the drill string 105 and directional tool 100 will, forexample, move the upper wall-engagingmember 107a inwardly and the lowerwall-engaging member 108a outwardly to impose a generally downwardlyacting lateral force' on the drill bit 106 and produce a correspondingchange in its direction. Each quarter-revolution of the drill string 105will, of course, similarly impose a downwardly acting force on the drillbit 106 so as to continue diverting the drill bit in the selecteddirection.

' To selectivelyopen and close the various valves 136 without requiringa specific angular orientation of an actuator (such as the actuator 125in FIG. 16) with the tool housing 101, an actuator 125' as=illustratedin FIG. 19 can be employed. As depicted there, the actuator 125'includes a tubular body 145 having an axial bore 146 whichis temporarilyclosed near the upper end of the body 145 by a frangible transversepartition 147. A sealing member, such as a typical swab cup 148, ismounted around the actuator body 145 so that the actuator 125 can bepumped downwardly through the drill string 105.

' longitudinal positions therealong. In this manner, wheneverwall-contacting member 108a. Similarly, the second upper wall-contactingmember 1071: will be connected to the lower wall-contacting member1081); and the third and fourth valves being open will respectivelyconnect the upper wall-contact ing members 107c and 107d to the lowerwall-contacting members 1086 and 108d. It will be realized that theother I2 valves 136 in the lower three tiers will remain closed. Simul--taneous opening of the valves in the second, third, or fourth tierswill, of course, change the order of connection between the upper andlowerwall-engaging means 102 and 103 to one of the other three possibleconnection patterns.

Turning now to FIG. 18, a cross-sectional view is shown of one of thevalves 136. Asillustrated, the valve 136 is comprised of a cylindricalbody 137 having longitudinally spaced enlarged-diameter shoulders I38and 139 and a longitudinally extending forward end 140. The valve body137 is slidably 141 and engaged with the rearward body end. In itsdepicted normally closed position, the passages 114d and 12011 in thethe valve actuator 125 is pumped through the drill string 105, it willpass through the array of valves 136 with its lower end coming to reston an upwardly directed shoulder 152 formed around the internal wall ofthe tool housing 101 immediately below the valves. Thus, when forexample, the slidable collar 151 isreleasably secured in the full-lineposition illustrated in FIG. 19, the four valves 136 in the uppermosthorizontal tier will be open when their outer ends, as at 140, areengaged by the outer face of the collar. The remaining 12 valves 136 inthe other three horizontal tiers will, of course, still be closed bytheir respective biasing springs 144.

It will be appreciated, therefore, that with the directional drillingtool illustrated in FIGS. 11 and 12 and including either the controlmeans 104 (as shown in FIGS. 1315) or the control means 104' (as shownin FIGS. 17 and 18), the deviation-sensing means 102 can beinterconnected to the direction-guiding means 103 as required'foraccomplishing any one of four desired changes of direction of the drillbit 106. Where the control means 104 are included with the directionaldrilling tool 100, the tool is selectively operated by means offour'specially arranged actuators'such as illustrated at 125 in FIG. 16;As previously described, so long as none of the actuators 125 arepositioned within the directional drilling tool 100, the annular valvemember 117 will remain in its neutral position depicted in FIG. 15. Thiswill, of course, enable the drill bit 106 and the directional tool 100to be lowered by the drill string to a desired position in the borehole123 without operating the wall-engaging means 102 and 103.

Once, however, it is determined that a change of direction of the drillbit 106 is desired, the appropriate one of the four actuators 125 isselected for insertion into the drill string 105. For example, if it isdesired to urge the drill bit 106 downwardly, the actuator 125particularly illustrated in FIG. 16 will be dispatched through the drillstring 105 and into the directional drilling tool 100. Once the valveactuator 125 comes to rest with its outstanding guide lug 129 resting onthe upwardly facing shoulder at the bottom of the groove 13], the cam124 will have entered the spiralled groove portion 133 to progressivelycam the annular valve member 117 to the left (as viewed in FIG. of itsillustrated neutral position. This will, of course, place each of theports 121 respectively in communication with the left-hand branchpassage 120 in each of the four depicted groups. For example, the valveport 121a will be in communication with the branch passage 120a andconduit 119a so that the inward movement of the wall-engaging member107a will produce a corresponding outward movement of the lowerwall-engaging member 108a. Similarly, inward movements of the upperwall-engaging members 107b-107d will respectively produce correspondingoutward movements of the lower-engaging members 10811-10811.

Accordingly, it will be appreciated from viewing FIG. 11

that as the drill string 105 is rotated, one ofthe upper wall-engagingmembers 107 will come into contact with the lower surface of theborehole 123 during each quarter of a given revolution. When thisoccurs, the combined weight of the drill string 105 and directional tool100 will, for example, move the upper wall-engaging member 1070,inwardly and the lower wall-engaging member 1080 outwardly to impose agenerally downwardly acting lateral force on the drill bit 106 andproduce a corresponding change in its direction. Each quarter-revolutionof the drill string 105 will, of course, similarly impose a downwardlyacting force on thedrill bit 106 so as to continue diverting the drillbit in the selected direction.

As previously mentioned, the course of the drill bit 106 may be reliablyascertained by periodic surveys with suitable borehole-surveyingdevices. Thus, if it is determined that a change in direction isrequired, the particular valve actuator 125. that is then in thedirectional drilling tool 100 is withdrawn to restore the valve member117 to its illustrated neutral position. The appropriate one of theother three valvev actuators 125 is then simply dispatched through thedrill string 105 by either allowing the actuator to fall free or bypumping it downwardly by the circulation of the drilling fluid. Oncethis second actuator 125 is in position, the valve member 1 17 will havebeen shifted to the selected operating position. On the other hand, ifno further change in course is required, so long as no valve actuator125 is positioned within the directional drilling tool 100, the upperand lower wall-engaging means 102 and 103 will be isolated from oneanother by the neutrally positioned control means 104 to permit thedrilling tocontinue in the usual manner.

The operation of the directional drilling tool 100 including thealternative control means 104' is, of course, generally similarl It willbe appreciated, however, that instead of having four distinctive valveactuators, the valve actuator 125 is selectively adjustable forinterconnecting the upper and lower wall-engaging means 102 and 103 inany one of their four possible operating arrangements. For example, ifit is desired to deviate the drill string bit 106 downwardly such-aspreviouslydescribed, the slidable collar 151- is simply left in thefull-line position illustrated in FIG. 19. In this manner, when thevalve actuator 125 comes to rest with its lower end shouldered on theinternal housing shoulder 152, the slidable collar 151 will open onlythe four valves 136 in the uppermost horizontal tier of valves asillustrated inFlG. I7 and leave the other 12 valves closed. Opening ofthese four upper valves 136 will, of course, operatively couple theupper wall-engaging member 1070 to the lower wall-engaging member 1080and similarly couple the Mali-engaging members 10712-10711 with thelower wall-engaging members 108b-108d respectively. As previouslydescribed, this operating arrangement will produce the desireddownwardly acting force on the drill 106 for each quarter-revolution ofthe drill string 105.

' If it is desired to discontinue the deviation of the drill bit 106,removal of the valve actuator 125 will reclose the four previouslyopened valves 13650 as to again block fluid communication between theupper and lower wall-engaging means 102 and 103. Repositioning ofthe-.slidable' collar 151 to any one of the three other longitudinallyspaced positions on the actuator body 145 will, of course, readilyprovide the other three operating arrangements.

It should be noted that the easily ruptured transverse partition 147 inthe actuator body 145 will allow the valve actuator 125' to be readilypumped downwardlythrough the drill string 105. Then, to be certain thatthe val've. ac tuator 125 is aetually in position with its lower endabutting the inwardly directed housing shoulder 152, the pumpingpressure of the circulating 'mud is simply increased to rupture thetransverse partition 147 and the resulting decrease in pump pressurewill provide a positive indication at the surface that the valveaetuator is, in fact, positioned within the directional drilling tool100. This transverse partition 147 is, of course, readily replaceable sothat the valve actuator 125' can be reused as necessary.

DESCRIPTION OF THETOOL DEPICTEDIN FIGS. 20-24 Turning now to FIG. 20, analternative embodiment is.

shown of a directional drilling tool 200 that is similar in manyrespects to the directional drilling tools 30 and 100 previouslydescribed but which incorporates selectively operable control means 201adapted to transmit fluid pressure between wallen a in deviation-sensingmeans 202 and directionuidin 8 g 8 E g means 203 respectively mounted onthe upper and lower ends of the tool housing 204. Although the upper andlower wallengaging means 202 and 203 could also be arranged in the samemanner as the wall-engaging means 102 in FIG. 12, as best seen in FIG.21, the upper wall-engaging means 202 preferably include four laterallymovable pistons 205 respec- -tively disposed in outwardly facing radialbores 206 arranged at 90 intervals around the tubular housing 204. Acircumferential band 207 is loosely mounted around the housing 204between enlarged shoulders, as at 208 and 209, with four wallcontactingmembers 210 being mounted on the band respectively adjacent to the outerends of the pistons 205. The lower wall-engaging means 203 are similarlyarranged and include four radially disposed pistons 211 that aredisposed in radial bores 212 for outward movement against a looselymounted circumferential band 213 carrying four equally spacedwallcontacting members 214.

The'upper piston cylinders 206 are filled with a suitable hydraulicfluid and respectively connected by fluid conduits such as tubing linesor fluid passages 215 through the housing 204 to the control means 201.Similarly, the lower piston cylinders 212 are separately filled with ahydraulic fluid; and these four cylinders are connected by fluidconduits 216 which are in turn respectively connected to four branchconduits such .as tubing lines or-fluid passages 217-220 extending fromthe lower wall-engaging means 203 through the housing 204 to the controlmeans 201.

Although the control means 201 are similar in many respects to thecontrol means 104' illustrated in FIG. 17, the control means 201 arearranged for transmitting fluid pressure between the upper and lowerpistons 209 and 211 without there being any direct fluid communicationtherebetween. To accomplish this, as best seen in FIGS. 20 and 23, theselectively operable control means 201 are comprised of a plurality ofpistons 221-224 respectively mounted in complementary longitudinalchambers 225-228 in the tool housing 204.

Each of these control pistons 221-224 are comprised of a up er and lowerpiston cylinders 206 and 212; and whenever an increase in fluid pressureis developed by one of the upper pistons, its associated control pistonwill be moved correspondingly so as to transmit the increased fluidpressure to the lower piston.

Accordingly, assuming that any given one of the 16 control pistons, suchas 2240, is free to move within its complementary chamber 228a, inwardmovement of its associated upper piston mem ber 205a will develop anincreased hydraulic pressure which will be immediately effective forshifting the control piston downwardly in relation to the tool body 204.This downward movement will, of course, produce a correspondingincreased hydraulic pressure in the piston cylinder 228a which is, inturn, transmitted to whichever one of the lower pistons 211 the pistonchamber is then connected to.

To control the movement of the pistons 221-224, the control pistons arenormally retained in a neutral position by selectively operable releasemeans which, in the preferred manner of accomplishing this, include alatch 'member, such as at 234, that is cooperatively mounted in theinternal wall of the tool housing 204 for radial movement inwardly andoutwardly. Stop means, such as a reduced-diameter groove 235, areprovided on the control piston 221a for selective engagement with thefree end of the movable latch member 234. To selectively actuate themovable latch member 234, an actuator 236 is pivotally mounted, as at237, to the tool housing 204 within an internal housing recess 238 andcoupled as at 239 to the inner end of the latch member. To normallymaintain the latch member 234 in engagement with the control piston221a, a spring, as at 240, is mounted in the recess 238 for normallyurging the latch member into the reduced-diameter groove 235.

By shaping the lower end of the actuator 236 so as to normally projectinwardly a short distance into the axial housing bore 241, inwardmovement of the curved end 242 of the actuator will be effective forretracting the latch member 234 form engagement with thereduced-diameter groove 235 on the piston 221a. Thus, once the latchmember 234 is withdrawn from the groove 235, the control piston 2210will be free for longitudinal movement upwardly and downwardly withinits associated cylinder 225a. Once, however, the actuator 236 is freedfor movement by the spring 240 to return the latch member 234 inwardly,the latch will reenter the groove 235 whenever the control piston 221anext reaches its neutral or intermediate position as illustrated.

It will be appreciated, therefore, that by arranging the selectivelyoperable control means 201 with l6'identical control pistons as at221-224 and their respective actuators as at 234, each of the four upperpiston cylinders 206 can be selectively coupled to each of the fourlower piston cylinders 212 in any one of the four possible arrangements.Thus, by arranging the fluid passages 214, 216 and 217-220 and the upperand lower pistons 205 and 211 as illustrated in FIG. 23, any one of thefour possible operating arrangements can be readily obtained by.selectively releasing a selected group of fourof the control pistons221-224 while leaving the remaining 12 control pistons latched in theiriittermediate positions. In the preferred. manner of accomplishing this,each vertical tier of four control pistons 221-224 is respectivelycoupled to one of the upper piston cylinders 206 by the fluid passages214. Then, each of the four piston cylinders 206 in the same horizontaltier are in turn respectively coupled by the individual fluid passages217-220 to each of the four lower piston cylinders 212. Thus, whenever,for example, the four control pistons 224a-224d in the upper horizontaltier are released for free axial movement, each of the four upper pistoncylinders 206a-206d will be respectively coupled to one of the fourlower piston cylinders 2120-21211.

To actuate the selectively operable control means 201, a tool such asshown in FIG. 19 is arranged for movement into the axial housing bore241 for selectivelyoperating any four of the actuators 236 in agivenhorizontal tier. It should be noted that irrespective of which four ofthe lb'actuators 236 are to be depressed at a given time, passageof theactuating tool through the housing bore 241 may momentarily release someor possibly all ofthe other 12 control pistons.221224 which are supposedto remain latched. This, however, will ,not present any particularproblem-inasmuch as the continued rotation of the directional-drillingtool 200 will quickly return the 12 momentarily released control pistons221-224 to their neutral positions as the upper and lower pistons 205and 211 respectively associated therewith are moved inwardly andoutwardly by the weight of the rotating drilling tool and its associateddrill string (not shown). Thus, once any one of these 12 control pistons221-224 passes its intermediate or neutral position, the latch member234 respectively associated therewith will be urged inwardly into thelocking groove 235 to lock the piston in its neutral position.Thereafter, inasmuch as the selected four actuators 236 will be heldinwardly for retracting the selected four latch members 234, only thesefour control pistons 221-224 will be free to move in accordance with thesuccessive movement of the upper pistons 205.

It will be appreciated that since the particular arrangement illustratedin FIGS. 20-22 only enables the control pistons 221-224 to either moveor not to move, there may be situations in which the correspondingmovements of the lower wall-engaging means 203 should be reduced.Accordingly, to accomplish this,.the control pistons 221-224 illustratedin FIG. 20 may be replaced with control pistons as illustrated at 243 inFIG. 24. As seen there, the piston members 243 have a plurality of steps244-246 formed around the intermediate portion of their body 247 forlimiting the axial travel thereof to three progressively larger spans oftravel. Thus, by forming thepiston body 247 with the longitudinallyspaced reduceddiameter portions 244-246, the piston 243 may beselectively latched in its intermediate position or alternativelypermitted to move axially in any one of three spans of travel.

To actuate the latch member 234, a tool such as that illustrated in FIG.19 is employed except that the selectively positioned annular collar (asat 151 employed thereon is replaced with similar collars (not shown)having different external diameters so as to determine the degree ofwithdrawal of the latch member 234 as required. Thus, for example, ifonly the minimum travel of the control piston 243 is to be permitted,the collar (such as that at 151 in FIG. 19) is selected to have aminimum external diameter so that the latch member 234 will be onlypartially retracted for limiting the actual travel of the piston 243 tothe span of travel defined between the shoulders 245. Similarly, byproviding an annular collar (as at 151) of slightly larger diameter,whenever this collar comes into'contact with the free end 242 of theactuator 236, the latch member 234 will be withdrawn still further so asto limit the span of travel of the piston 243 to that length defined bythe longitudinal spacing between the shoulders 246. Full retraction ofthe latch member 234 will, of course, permit the piston 243 to travelthe full length of the cylinder 248.

It will, of course, be appreciated that the directional-drilling tool200 will function in the same manner asthe directiona|-' drilling toolhaving the control means 104' depicted in FIG. 17. Thus, for the sake ofbrevity, it is believed necessary only to point out that operation ofthe tool 200 is conducted with an actuator such as illustrated in FIG.19 and describe immediately above. 1

DESCRIPTION OF THE TOOL DEPICTED IN FIGS. 25-28 It will be recognized,of course, that there may be situations:

in which it will be preferred to operate the directional drilling toolsof the present invention by manipulation of the drill string.Accordingly, as shown in FIG. 25, a directional drilling tool 300 isdepicted in which control means 301 are adapted ously described as, forexample, in FIG. 12, it is not believed necessary to illustrate theirconstruction in detail. Similarly, the control means 301 preferablyinclude an annular valve member 304 arranged in generally the samemanner as the valve member 52 illustrated in FIG. 6 for controllingfluid communication through various passages between the upper and lowerwall-engaging means 302 and 303.

To control the annular valve member 304, the directional drilling tool300 is arranged with an elongated tubular body 305 on which the upperand lower Wallengaging means 302 and 303 and drill bit 306 arerespectively mounted. A tubular mandrel 307 is telescopically arrangedin the upper portion of the tool body 305 and coupled, as by an enlargedsection 308, to the lower end of the drill string 309. As seen in FIGS.25 and 26, the mandrel 307 is corotatively secured to the tool body 305by longitudinal splines and mating grooves as at 310 for transmittingrotation from the drill string 309 to the drill bit 306. The mandrel 307is, however, free to move longitudinally from its elevated positiondepicted in FIG. 25 downwardly until the enlarged mandrel portion 308engages the upper face of the shoulder 31] on top of the body 305.Conversely, the upper limit of travel of the mandrel 307 in relation tothe tool body 305 is determined by the upper end of the splines 310 onthe'mandrel coming into abutment with the lower face of the shoulder311. p

It will be appreciated, therefore, that once the directional drillingtool 300 ispositioned within a borehole, the mandrel 307 can be movedover a limited span of longitudinal travel in relation to the tool body305 by simply picking-up and slacking-off the drill string 309.Accordingly, to utilize this longitudinal travel of the mandrel 307 forselectively shifting the annular valve member 304, adependingtubularextension 312 ((FlG. 27) of the mandrel is provided with one or twolaterally extending cam followers or rollers 313 that are adapted forreception in a system 324 of alternating channels or grooves fonnedaround the cireumferenceof the internal wall of the valve member.

As best seen in FIG. 28, the groove system 314 is preferably arranged asa series of upwardly inclined grooves 315 alternately disposed between aseries of downwardly inclined grooves 316. As illustrated, the junctionsof the grooves 315 and 316 at the upper and lower faces of the valvemember 304 are respectively arranged to provide entrance and exitopenings 317 and 318 at circumferentially spaced intervals around thevalve'member, with the upper openings being staggered in relation tothe'lower openings. To accommodate the cam roller or rollers 313,vertical grooves 319 and 320 are formed in the internal wall of the toolbody 305 so that the cam rollers can pass above and-below the valvemember 304 as the mandrel 307 is reciprocated in relation to the toolbody.

Accordingly, it will be appreciated that by arranging the inclinedgroove system 314- as illustrated, each downward stroke of the mandrel307 will shift the annular valve member 304 through an are equal to theangular separation of two immediately adjacent entrance and exitopenings 317 and 318; and, conversely, each upward stroke of the mandrelwill be effective to index the valve member so as to bring thenext-following entrance opening into alignment with the upper groove319. Thus, in the preferred arrangement of the tool 300, an upwardstroke of the mandrel 307 followed by a downward stroke is required toindex the-valve member 304 to its next effective position. I

It will be recognized, therefore, that the angular spacing between twosuccessive exit openings 318 should preferably correspond to the angularspacing between adjacent ports (such as those shown at 550 and 55b inFIG. 6). Thus, to index the annular valve member 304 from one operatingposition to its next, a-consecutive upward stroke and a single downwardstroke of the mandrel 307 are required. With four sets of upper andlower wall-engaging means 302 and 303, four consecutive reciprocatingstrokes of the mandrel 307 will progressively index the annular valvemember 304 to its four operating positions. The fifth reciprocation ofthe mandrel 307 will index the valve member 304 to its neutral positionfor blocking communication between the upper and lower wallengagingmeans 302 and 303; and the sixth reciprocation-of the mandrel willreturn the valve member to its firstoperating position. It will be alsoseen that by arranging the"valve member 304 to be in one of its fivepositions (its four operating positions and its neutral position) whenthe mandrel 307 is fully telescoped into the tool body 305, the abutmentof the shoulders 308 and 311 will enable the weight o f the drill string309 to be imposed on the drill bit 306 during the operation of the tool300. Y

SUMMARY With the directional tool 30 depicted in FIGS. 1-10, control'ofthe drilling bit coupled thereto is simply accomplished by regulatingthe pressure of the drilling fluid or mud circulating through thesystem. On the other hand, the directional drilling tools and 200respectively shown in FIGS. 11 19 and FIGS. 20-24 are adapted to becontrolled by special purpose actuating tools as illustrated in FIGS. 16and 19 which are dispatched through the drill string. The directionaltool 300 is adapted for selective operation by manipulating the drillstring to position the control means thereof in any one of severalcontrol positions. 7

Accordingly, it will be appreciated that the present invention hasprovided new and improved methods and apparatus for guiding a drill bitas it progressively excavates a borehole. By employing any of theseveral directional drilling tools disclosed herein, a drill bit coupledthereto can be reliably directed in any of several selected directionsduring the course of a drilling operation without requiring the removalof the adjustments a borehole is being excavated and comprising: a bodyadapted for connection in a drill string including a borehole-excavatingdevice; deviation-sensing means on said body and adapted for developingpressures upon lateral movements of said body toward a borehole wallduring the excavation of a borehole by a borehole-excavating devicecoupled to said body; guiding means on said body and responsive topressures applied thereto for shifting said body laterally in relationto the axis of a borehole being excavated by a borehole-excavatingdevice coupled to said body; and control means operable from the surfacefor selectively coupling said deviation-sensing means to-said guidingmeans for operation of said guiding means in response to pressuresdeveloped by said deviation-sensing means.

2. The apparatus of claim 1 whereinsaid deviation-sensing means and saidguiding means are angularly displaced so that their respective movementsare in different lateral directions.

3. The apparatus of claim 1 wherein said control means in- I elude firstand second fluid conduits respectively coupled to said deviation-sensingmeans and said guiding means, a conever said valve member is in selectedpositions; and said actuating means include a pressure-responsiveactuating I member adapted for moving said valve member to its saidselected positions in response to predetermined changes in the fluidpressure within a drill string coupled to said body.

5. The apparatus of claim 3 wherein said control member is" a valvemember adapted for opening and closing fluid communication between saidfirst and second fluid conduits whenever said valve member is inselected positions; and said aetuating means include an actuator adaptedfor passage through a drill string coupled to said body to apredetermined position relative to said body, and means on said actuatorand. said valve member adapted for shifting said valve member to. itssaid selected positions whenever said actuator is moved into and out ofits said predetermined position.

6. The apparatus of claim 3 wherein said actuating means include anactuating member movably mounted-on said body and adapted for connectionto such a drill string, and means cooperatively arranged between saidactuating-member and said control member and adapted for selectivelymoving said control member upon movements of such a drill string.

7. The apparatus of claim 6 wherein said control member is a valvemember movably mounted on said body andadapted for opening and closingfluid communication betweensaid first and second fluid conduits as saidvalve member is selectively moved.

8. Apparatus adapted for controlling the direction in which.

a borehole is being excavated and comprising: a body adapted forconnection in a drill string including a drill bit adapted forexcavating a borehole; first wall-engaging means on said body andadapted for movement inwardly in response to forces urging said bodylaterally against a borehole wall during the ex-. cavation of a boreholeby a drill bit connected thereto; second wall-engaging meanslongitudinally spaced from said first wallengaging means on said bodyand adapted for movement outwardly in relation thereto for shifting saidbody laterally in. relation totthe axis of a borehole being excavated bysuch'a drill bit; and control means operable from the surface toselectively intercouple said first and second wall-engaging means forcooperatively urging said second wall-engaging means outwardly against aborehole wall in response to inward movements of said firstwall-engaging means to direct such a drill. bit along a selected axis ofexcavation.

9. The apparatus of claim 8 wherein said firstwall-engaging meansinclude pressure-developing means adapted for developing fluid pressuresin response to said inward movements of said first wall-engaging means;said second wall-en:- gaging means include pressure-actuated meansadapted for moving said second wall-engaging means outwardly in responseto fluid pressures developed by said pressuredeveloping means; and saidcontrol means include first and second fluid conduits respectivelycoupled'to said pressuredeveloping means and said pressure-actuatedmeans, a control member adapted for movement on said body forselectively regulating communication between said first and second fluidconduits, and actuating means operable from the surface for selectivelymoving said control member.

10. The apparatus of claim 9 wherein said pressure-develop ing means andsaid pressureactuated means are angularly displaced so that theirrespective movements are in different. lateral directions.

11. The apparatus of claim 9 wherein said actuating means include apressure-responsive actuating member adapted to be coupled to saidcontrol member for moving said control member in response topredetermined changes in the fluid pressure within a drill stringcoupled to said body.

12. The apparatus of claim 11 wherein said control member is a valvemember adapted for opening and closing fluid communication between saidfirst and second fluid conduits whenever said valve member is inselected positions.

13. The apparatus of claim 8 wherein said first wall-engaging meansinclude pressure-developing means adapted for developing fluid pressuresin response to said inward move-. ments of said first wall-engagingmeans; said second wall-engaging means include pressure-actuated meansadapted for moving said second wall-engaging means outwardly in responseto fluid pressures developed by said pressuredeveloping means; and saidcontrol means include first and second fluid conduits respectivelycoupled to said pressuredeveloping means and to said pressure-actuatedmeans, a control member adapted for movement between spaced positions onsaid body for selectively regulating communication between said firstand second fluid conduits, an actuator adapted for passage through adrill string coupled to said body to a predetermined position relativeto said body, and means on said-actuator and said control member adaptedfor shifting said control member between its said spaced positionswhenever said actuator is moved into and out of its said predeterminedposition.

14. The apparatus ofclaim 13 wherein said control member is a valvemember adapted for opening and closing fluid communication between saidfirst andsecond fluid conduits wheneversaid valve member is in differentones of its said spaced positions.

15. The apparatus of claim 13 wherein said control member is a pistonmember operatively disposed in a cylinder and adapted forblockingpressure communication between said firstand second fluid conduitswhenever said piston member is retained in one of its said spacedpositions within said cylinder and for transmitting fluid pressurebetween said first and second conduits whenever said said piston memberis free to move between its said spaced positions within said cylinder;and further including means on said body adapted for releasablyretaining said piston member in its said one position; and means adaptedfor cooperation with said pistonretaining means upon movement of saidactuator to its said selected position for releasing said piston memberfor move: mentbetween its said spaced positions.

16. The apparatus of claim 8 wherein said first wall-engaging meansinclude pressure-developing means adapted for developing fluid pressuresin response to said inward movements of said first wall-engaging means;said second wall-engaging means include pressure-actuated means adaptedfor moving said second wall-engaging means outwardly in response tofluid pressures developed by said pressuredeveloping means; and saidcontrol means include first and second-fluid conduits respectivelycoupled to said pressuredeveloping means and to said pressure-actuatedmeans, a control member on said body adapted for movement betweenpredetermined spaced positions for selectively regulating communicationbetween said first and second fluid conduits, an actuating membermovably mounted on said body and adapted for connection to such a drillstring, and means cooperatively-arranged between said actuating memberand said control member for moving said control member between its saidspaced positions in response to movements of said actuating memberinrelation to said body by a drill string connected to said actuatingmember.

17. The apparatus of claim 16 wherein said control member is a valvemember adapted for opening and closing fluid communication between saidfirst and second fluid conduits'whenever said valve member is indifferent ones of its said spaced positions.

18. The apparatus of claim 16 wherein said firstand second wall-engagingmeans are angularly displaced so that said first and secondwall-engaging means are movable in different lateral directions.

19. A directional drilling tool comprising: an elongated body having alongitudinal passage therethrough and adapted for connection in arotating drill string including a boreholeexcavating device; first andsecond wall-engaging means longitudinally spaced on said body andincluding first and second groups of pistons operatively mounted on saidbody for movement respectively along first and second sets of angularlyspaced lateral axes between retracted and extended positions in relationto said body; and control means adapted for selectively intercouplingsaid first and second wall-engaging means and including first and secondconduits respectively fluidly coupled to said first and second groups ofpistons. valve means movably mounted on said body for movement betweenspaced positions and operatively arranged for selectively regulatingcommunication between said first and second conduits in accordance withthe position of said valve means, and actuating means operable from thesurface for selectively moving said valve means between its said spacedpositions while said tool is in a borehole.

20. The directional drilling tool ofelaim 19 wherein each of saidpistons is fluidly coupled to only one of said conduits; and said valvemeans are movable to a sufficient number of said spaced positions toenable each of said first pistons to be fluidly coupled to each of saidsecond pistons in successive ones of said spaced positions of said valvemeans.

21. The directional drilling tool of claim 20 wherein said valve meansare also arranged for movement to another one of said spaced positionsto isolate said first conduits from said second conduits.

22. The directional drilling tool of claim 20 wherein said valve meansinclude a valve member operatively arranged on said body for rotation inrelation thereto between angularly spaced positions; and said actuatingmeans include a pressureresponsive actuating member adapted for movementin response to predetermined changes in the fluid pressure within adrill string coupled to said tool, and cam means operatively arrangedbetween said members for progressively rotating said valve member toeach of its said positions upon successive mc -/cments of said actuatingmember.

23. The directional drilling tool of claim 20 wherein said valve meansinclude a valve member operatively arranged on said body for rotation inrelation thereto between angularly spaced positions; and said actuatingmeans include a plurality of actuator members respectively adapted forpassage through a drill string coupled to said tool and to apredetermined position in relation to said body, and individuallydistinctive cam means on each of said actuator members and said valvemember for selectively rotating said valve member to a predetermined oneof each of its said positions according to which one of said actuatormembers is in said predetermined position.

24. The directional drilling tool of claim 20 wherein said valve meansinclude a'valve member operatively arranged on said body for rotation inrelation thereto between angularly spaced positions; and said actuatingmeansinclude an actuating member adapted for coupling to a drill stringand operatively arranged for reciprocating movement in relation to saidbody upon reciprocation of such a drill string, and cam meansoperatively arranged between said members for progressively rotatingsaid valve member to each of its said positions upon successivereeiprocations of said actuating member.

25. A directional drilling tool comprising: an elongated body having alongitudinal passage therethrough and adapted for connection in arotating drill string including a boreholeexcavating device; first andsecond wall-engaging means longitudinally spaced on said body andincluding first and second groups of pistons operatively mounted thereonfor movement respectively along first and second sets of angularlyspaced lateral axes between retracted and extended positions in relationto said body; and control means adapted for selectively intercouplingsaid first and second wall-engaging means and including first and secondconduits respectively fluidly coupled to said first and second groups ofpistons with each of said pistons being fluidly coupled to only one ofsaid conduits, a plurality of movable members operatively arranged onsaid body with each of said movable members being respectively coupledto one of said first conduits and one of said second conduits forselectively regulating communication between only the two conduitscoupled thereto independently of the operation of the others of saidmovable members, and actuating means operable from the surface forselectively moving each of said movable members independently of saidothers so as to selectively intercouple said first and secondwall-engaging means in different predetermined arrangements fordirecting such a borehole-excavating device along selected axes ofexcavation.

26. The directional drilling tool of claim wherein said ac tuating meansinclude an actuator member adapted for passage from the surface througha drill string coupled to said tool and to a predetermined position inrelation to said body, and means cooperatively arranged on said movablemembers and said actuator members for moving only selected ones of saidmovable members to operating positions for establishing desired onesolsaid predetermined arrangements.

27. The directional drilling tool of claim 26 wherein said movablemembers are valve members respectively adapted for opening and closingfluid communication between said two conduits coupled thereto.

28. The directional drilling tool of claim 26 wherein said movablemembers are piston members respectively disposed ina cylinder andadapted for blocking pressure communication between said two conduitscoupled thereto whenever that piston member is retained in a fixedposition within its respective cylinder and for transmitting fluidpressure between said two conduits coupled thereto whenever that pistonmember is free to move within its respective cylinder.

29. The directional drilling tool of claim 28 wherein said actuatingmeans include: means on said body adapted for releasably retaining saidpiston members .in their respective said fixed positions, an actuatingmember adapted for passage from the surface through a drill stringcoupled to said tool and to a predetermined position in relation to saidbody, and means cooperatively arranged on said actuating member andengageable with said piston-retaining means for releasing only selectedones of said piston members for free movement within their respectivecylinders for establishing desired ones of said predeterminedarrangements.

30. A directional drilling tool comprising: a first tubular memberhaving a longitudinal passage therethrough and adapted for connection toa borehole-excavating device; a second tubular member adapted forconnection to a rotating drill string corotatively secured to said firstmember and having at least a lower portion extending into saidlongitudinal passage for movement between spaced positions therein uponupward and downward movements of said second member relating to saidfirst member; first and second wall-engaging means longitudinally spacedon said first member and including first and second groups of pistonsoperatively mounted thereon for movement respectively along first andsecond sets of angularly spaced lateral axes between retracted andextended positions in relation to said first member; and control meansadapted for selectively intercoupling said first and secondwall-engaging means and including first and second conduits respectivelyfluidly coupled to said first and second groups of pistons with each ofsaid pistons being coupled to only one of said conduits, a valve memberon said first member adapted for movement relative thereto betweenpredetermined operating positions for selectively regulating fluidcommunication between said first and second conduits, and meanscooperatively arranged in said longitudinal passage between said valvemember and said lower portion of said second member and responsive tomovements thereof between its said spaced positions for moving saidvalve member between its said operating positions.

31. The directional drilling tool of claim 30 wherein said valve memberis an annular member rotatably mounted on said first member; and saidvalve moving means include an alternating cam-guiding track formedaround said annular valve member and defining successive angularlyspaced stops, and a cam member on said lower portion of said secondmember received in said cam-guiding track and adapted for progressivelyrotating said valve member to each of its said operating positions assaid cam member is moved to each of said angularly spaced stops.

32. A method for excavating a borehole along a desired course with atool coupled to a tubular drill string extending to the surface, saidtool having a drill bit coupled thereto and including firstwall-engaging means thereon adapted for movement inwardly in response toforces urging said tool against a borehole wall during excavation of aborehole, second wall-.

engaging means thereon adapted for movement outwardly against a boreholewall for shifting said tool and drill bit laterally in relation to theaxis ofa borehole being excavated, and control means operable from thesurface for selectively connecting said first and second wall-engagingmeans, com- 2'1 prising the steps of: rotating said drill string foroperatively driving said drill bit to progressively excavate saidborehole further; and, as said tool is rotated by said drill string,operating said control members from the surface for selectivelyconnecting said first and second wall-engaging means to move the surfacethrough said drill string to said tool.

35. The method of claim 32 wherein said control means are selectivelyoperated by predetermined movements of said drill string in relation tosaid tool. I

36. The method of claim 32 further including the step of measuring atleast one parameter indicative of the course of said borehole todetermine the extent that said drill bit has been shifted.

37. The method of claim 36 further including the step of operating saidcontrol members from the surface for disconnecting said first and secondwall-engaging means to discontinue further shifting ofsaid drill bit.

2. The apparatus of claim 1 wherein said deviation-sensing means andsaid guiding means are angularly displaced so that their respectivemovements are in different lateral directions.
 3. The apparatus of claim1 wherein said control means include first and second fluid conduitsrespectively coupled to said deviation-sensing means and said guidingmeans, a control member adapted for movement on said body forselectively regulating communication between said first and second fluidconduits, and actuating means operable from the surface for selectivelymoving said control member.
 4. The apparatus of claim 3 wherein saidcontrol member is a valve member adapted for opening and closing fluidcommunication between said first and second fluid conduits whenever saidvalve member is in selected positions; and said actuating means includea pressure-responsive actuating member adapted for moving said valvemember to its said selected positions in response to predeterminedchanges in the fluid pressure within a drill string coupled to saidbody.
 5. The apparatus of claim 3 wherein said control member is a valvemember adapted for opening and closing fluid communication between saidfirst and second fluid conduits whenever said valve member is inselected positions; and said actuating means include an actuator adaptedfor passage through a drill string coupled to said body to apredetermined position relative to said body, and means on said actuatorand said valve member adapted for shifting said valve member to its saidselected positions whenever said actuator is moved into and out of itssaid predetermined position.
 6. The apparatus of claim 3 wherein saidactuating means include an actuating member movably mounted on said bodyand adapted for connection to such a drill string, and meanscooperatively arranged between said actuating member and said controlmember and adapted for selectively moving said control member uponmovements of such a drill string.
 7. The apparatus of claim 6 whereinsaid control member is a valve member movably mounted on said body andadapted for opening and closing fluid communication between said firstand second fluid conduits as said valve member is selectively moved. 8.Apparatus adapted for controlling the direction in which a borehole isbeing excavated and comprising: a body adapted for connection in a drillstring including a drill bit adapted for excavating a borehole; firstwall-engaging means on said body and adapted for movement inwardly inresponse to forces urging said body laterally against a borehole wallduring the excavation of a borehole by a drill bit connected thereto;second wall-engaging means longitudinally spaced from said firstwall-engaging means on said body and adapted for movement outwardly inrelatioN thereto for shifting said body laterally in relation to theaxis of a borehole being excavated by such a drill bit; and controlmeans operable from the surface to selectively intercouple said firstand second wall-engaging means for cooperatively urging said secondwall-engaging means outwardly against a borehole wall in response toinward movements of said first wall-engaging means to direct such adrill bit along a selected axis of excavation.
 9. The apparatus of claim8 wherein said first wall-engaging means include pressure-developingmeans adapted for developing fluid pressures in response to said inwardmovements of said first wall-engaging means; said second wall-engagingmeans include pressure-actuated means adapted for moving said secondwall-engaging means outwardly in response to fluid pressures developedby said pressure-developing means; and said control means include firstand second fluid conduits respectively coupled to saidpressure-developing means and said pressure-actuated means, a controlmember adapted for movement on said body for selectively regulatingcommunication between said first and second fluid conduits, andactuating means operable from the surface for selectively moving saidcontrol member.
 10. The apparatus of claim 9 wherein saidpressure-developing means and said pressure-actuated means are angularlydisplaced so that their respective movements are in different lateraldirections.
 11. The apparatus of claim 9 wherein said actuating meansinclude a pressure-responsive actuating member adapted to be coupled tosaid control member for moving said control member in response topredetermined changes in the fluid pressure within a drill stringcoupled to said body.
 12. The apparatus of claim 11 wherein said controlmember is a valve member adapted for opening and closing fluidcommunication between said first and second fluid conduits whenever saidvalve member is in selected positions.
 13. The apparatus of claim 8wherein said first wall-engaging means include pressure-developing meansadapted for developing fluid pressures in response to said inwardmovements of said first wall-engaging means; said second wall-engagingmeans include pressure-actuated means adapted for moving said secondwall-engaging means outwardly in response to fluid pressures developedby said pressure-developing means; and said control means include firstand second fluid conduits respectively coupled to saidpressure-developing means and to said pressure-actuated means, a controlmember adapted for movement between spaced positions on said body forselectively regulating communication between said first and second fluidconduits, an actuator adapted for passage through a drill string coupledto said body to a predetermined position relative to said body, andmeans on said actuator and said control member adapted for shifting saidcontrol member between its said spaced positions whenever said actuatoris moved into and out of its said predetermined position.
 14. Theapparatus of claim 13 wherein said control member is a valve memberadapted for opening and closing fluid communication between said firstand second fluid conduits whenever said valve member is in differentones of its said spaced positions.
 15. The apparatus of claim 13 whereinsaid control member is a piston member operatively disposed in acylinder and adapted for blocking pressure communication between saidfirst and second fluid conduits whenever said piston member is retainedin one of its said spaced positions within said cylinder and fortransmitting fluid pressure between said first and second conduitswhenever said said piston member is free to move between its said spacedpositions within said cylinder; and further including means on said bodyadapted for releasably retaining said piston member in its said oneposition; and means adapted for cooperation with said piston-retainingmeans upon movement of said actuator to its said selected position forreleasing said piston membEr for movement between its said spacedpositions.
 16. The apparatus of claim 8 wherein said first wall-engagingmeans include pressure-developing means adapted for developing fluidpressures in response to said inward movements of said firstwall-engaging means; said second wall-engaging means includepressure-actuated means adapted for moving said second wall-engagingmeans outwardly in response to fluid pressures developed by saidpressure-developing means; and said control means include first andsecond fluid conduits respectively coupled to said pressure-developingmeans and to said pressure-actuated means, a control member on said bodyadapted for movement between predetermined spaced positions forselectively regulating communication between said first and second fluidconduits, an actuating member movably mounted on said body and adaptedfor connection to such a drill string, and means cooperatively arrangedbetween said actuating member and said control member for moving saidcontrol member between its said spaced positions in response tomovements of said actuating member in relation to said body by a drillstring connected to said actuating member.
 17. The apparatus of claim 16wherein said control member is a valve member adapted for opening andclosing fluid communication between said first and second fluid conduitswhenever said valve member is in different ones of its said spacedpositions.
 18. The apparatus of claim 16 wherein said first and secondwall-engaging means are angularly displaced so that said first andsecond wall-engaging means are movable in different lateral directions.19. A directional drilling tool comprising: an elongated body having alongitudinal passage therethrough and adapted for connection in arotating drill string including a borehole-excavating device; first andsecond wall-engaging means longitudinally spaced on said body andincluding first and second groups of pistons operatively mounted on saidbody for movement respectively along first and second sets of angularlyspaced lateral axes between retracted and extended positions in relationto said body; and control means adapted for selectively intercouplingsaid first and second wall-engaging means and including first and secondconduits respectively fluidly coupled to said first and second groups ofpistons, valve means movably mounted on said body for movement betweenspaced positions and operatively arranged for selectively regulatingcommunication between said first and second conduits in accordance withthe position of said valve means, and actuating means operable from thesurface for selectively moving said valve means between its said spacedpositions while said tool is in a borehole.
 20. The directional drillingtool of claim 19 wherein each of said pistons is fluidly coupled to onlyone of said conduits; and said valve means are movable to a sufficientnumber of said spaced positions to enable each of said first pistons tobe fluidly coupled to each of said second pistons in successive ones ofsaid spaced positions of said valve means.
 21. The directional drillingtool of claim 20 wherein said valve means are also arranged for movementto another one of said spaced positions to isolate said first conduitsfrom said second conduits.
 22. The directional drilling tool of claim 20wherein said valve means include a valve member operatively arranged onsaid body for rotation in relation thereto between angularly spacedpositions; and said actuating means include a pressure-responsiveactuating member adapted for movement in response to predeterminedchanges in the fluid pressure within a drill string coupled to saidtool, and cam means operatively arranged between said members forprogressively rotating said valve member to each of its said positionsupon successive movements of said actuating member.
 23. The directionaldrilling tool of claim 20 wherein said valve means include a valvemember operatively arranged on said body for rotation in rElationthereto between angularly spaced positions; and said actuating meansinclude a plurality of actuator members respectively adapted for passagethrough a drill string coupled to said tool and to a predeterminedposition in relation to said body, and individually distinctive cammeans on each of said actuator members and said valve member forselectively rotating said valve member to a predetermined one of each ofits said positions according to which one of said actuator members is insaid predetermined position.
 24. The directional drilling tool of claim20 wherein said valve means include a valve member operatively arrangedon said body for rotation in relation thereto between angularly spacedpositions; and said actuating means include an actuating member adaptedfor coupling to a drill string and operatively arranged forreciprocating movement in relation to said body upon reciprocation ofsuch a drill string, and cam means operatively arranged between saidmembers for progressively rotating said valve member to each of its saidpositions upon successive reciprocations of said actuating member.
 25. Adirectional drilling tool comprising: an elongated body having alongitudinal passage therethrough and adapted for connection in arotating drill string including a borehole-excavating device; first andsecond wall-engaging means longitudinally spaced on said body andincluding first and second groups of pistons operatively mounted thereonfor movement respectively along first and second sets of angularlyspaced lateral axes between retracted and extended positions in relationto said body; and control means adapted for selectively intercouplingsaid first and second wall-engaging means and including first and secondconduits respectively fluidly coupled to said first and second groups ofpistons with each of said pistons being fluidly coupled to only one ofsaid conduits, a plurality of movable members operatively arranged onsaid body with each of said movable members being respectively coupledto one of said first conduits and one of said second conduits forselectively regulating communication between only the two conduitscoupled thereto independently of the operation of the others of saidmovable members, and actuating means operable from the surface forselectively moving each of said movable members independently of saidothers so as to selectively intercouple said first and secondwall-engaging means in different predetermined arrangements fordirecting such a borehole-excavating device along selected axes ofexcavation.
 26. The directional drilling tool of claim 25 wherein saidactuating means include an actuator member adapted for passage from thesurface through a drill string coupled to said tool and to apredetermined position in relation to said body, and means cooperativelyarranged on said movable members and said actuator members for movingonly selected ones of said movable members to operating positions forestablishing desired ones of said predetermined arrangements.
 27. Thedirectional drilling tool of claim 26 wherein said movable members arevalve members respectively adapted for opening and closing fluidcommunication between said two conduits coupled thereto.
 28. Thedirectional drilling tool of claim 26 wherein said movable members arepiston members respectively disposed in a cylinder and adapted forblocking pressure communication between said two conduits coupledthereto whenever that piston member is retained in a fixed positionwithin its respective cylinder and for transmitting fluid pressurebetween said two conduits coupled thereto whenever that piston member isfree to move within its respective cylinder.
 29. The directionaldrilling tool of claim 28 wherein said actuating means include: means onsaid body adapted for releasably retaining said piston members in theirrespective said fixed positions, an actuating member adapted for passagefrom the surface through a drill string coupled to said tool and to apredeterMined position in relation to said body, and means cooperativelyarranged on said actuating member and engageable with saidpiston-retaining means for releasing only selected ones of said pistonmembers for free movement within their respective cylinders forestablishing desired ones of said predetermined arrangements.
 30. Adirectional drilling tool comprising: a first tubular member having alongitudinal passage therethrough and adapted for connection to aborehole-excavating device; a second tubular member adapted forconnection to a rotating drill string corotatively secured to said firstmember and having at least a lower portion extending into saidlongitudinal passage for movement between spaced positions therein uponupward and downward movements of said second member relating to saidfirst member; first and second wall-engaging means longitudinally spacedon said first member and including first and second groups of pistonsoperatively mounted thereon for movement respectively along first andsecond sets of angularly spaced lateral axes between retracted andextended positions in relation to said first member; and control meansadapted for selectively intercoupling said first and secondwall-engaging means and including first and second conduits respectivelyfluidly coupled to said first and second groups of pistons with each ofsaid pistons being coupled to only one of said conduits, a valve memberon said first member adapted for movement relative thereto betweenpredetermined operating positions for selectively regulating fluidcommunication between said first and second conduits, and meanscooperatively arranged in said longitudinal passage between said valvemember and said lower portion of said second member and responsive tomovements thereof between its said spaced positions for moving saidvalve member between its said operating positions.
 31. The directionaldrilling tool of claim 30 wherein said valve member is an annular memberrotatably mounted on said first member; and said valve moving meansinclude an alternating cam-guiding track formed around said annularvalve member and defining successive angularly spaced stops, and a cammember on said lower portion of said second member received in saidcam-guiding track and adapted for progressively rotating said valvemember to each of its said operating positions as said cam member ismoved to each of said angularly spaced stops.
 32. A method forexcavating a borehole along a desired course with a tool coupled to atubular drill string extending to the surface, said tool having a drillbit coupled thereto and including first wall-engaging means thereonadapted for movement inwardly in response to forces urging said toolagainst a borehole wall during excavation of a borehole, secondwall-engaging means thereon adapted for movement outwardly against aborehole wall for shifting said tool and drill bit laterally in relationto the axis of a borehole being excavated, and control means operablefrom the surface for selectively connecting said first and secondwall-engaging means, comprising the steps of: rotating said drill stringfor operatively driving said drill bit to progressively excavate saidborehole further; and, as said tool is rotated by said drill string,operating said control members from the surface for selectivelyconnecting said first and second wall-engaging means to move said secondwall-engaging means outwardly in response to inward movements of saidfirst wall-engaging means for shifting said drill bit in a selectedlateral direction.
 33. The method of claim 32 wherein said control meansare selectively operated by increasing the pressure of drilling fluidscirculating through said drill string to at least a predeterminedpressure.
 34. The method of claim 32 wherein said control means areselectively operated by dispatching an actuating member from the surfacethrough said drill string to said tool.
 35. The method of claim 32wherein said control means are selectively operAted by predeterminedmovements of said drill string in relation to said tool.
 36. The methodof claim 32 further including the step of measuring at least oneparameter indicative of the course of said borehole to determine theextent that said drill bit has been shifted.
 37. The method of claim 36further including the step of operating said control members from thesurface for disconnecting said first and second wall-engaging means todiscontinue further shifting of said drill bit.